Temperature Based Fan Controller can be used for reducing the power consumption & also to assist people who are disabled and are unable to control the speed of fan.It may also be used for monitoring changes in environment.

1. TEMPERATURE BASED FAN CONTROLLER
BYRICHA NIVEDITA

2. OBJECTIVE OF PROJECT
Our object of making this project is for reducing the power
consumption. And also to assist people who are disabled and are
unable to control the speed of fan.
It may also be used for monitoring changes in environment.
In near future, it can also be used in different industries and
electronic devices.

3. Introduction

A simple introduction about the temperature controller circuit.

This circuit project is mainly used for indicating temperature , controlling
temperature.

Microprocessor forms the processing part.

In temperature controller circuit, there are two parts consisting of
◦ ADC 0804 interface with AT89C52.
◦ LCD interface with AT89C52

The hardware circuit of temperature controller need the programming.

4. • There are two possibilities of programming :assembly language programming
c language

Programming is usually loaded in the AT 89C52 controller IC.

AT89C52 is a family of 8051.

The main principle of this project to indicate temperature and to control the
temperature.

5. COMPONENTS USED:
Microcontroller AT89C51

Resistor

Capacitor

DC power supply

LED

Switch

Transistor

Buzzer

Relay

Crystal Oscillator

ADC0804

Voltage Regulator

Temperature Sensor LM 35

LCD Display

Socket

Diode

Electric Fan 12V

Opt Coupler ILD74

6. COMPONENTS USED :1. MICROCONTROLLER AT89C51:
AT89C51 is an 8-bit microcontroller.

ATMEL 89C51 has 4KB of Flash programmable and
erasable read only memory (EPROM)

It has 128 bytes of RAM.

8 bit microcontroller, means it can read, write and process 8 bit
data.

Basically 8 bit specifies the size of data bus. 8 bit microcontroller
means 8 bit data can travel on the data bus.

8. RESISTOR:A resistor is a two-terminal electronic component that produces a
voltage across its terminals that is proportional to the electric current
through it in accordance with Ohm's law:
V = IR
The primary characteristics of a resistor are the resistance, the
tolerance, maximum working voltage and the power rating. Other
characteristics include temperature coefficient, noise, and inductance.

9. CAPACITOR:
The capacitor's function is to store electricity, or electrical energy.

The capacitor is constructed with two electrode plates facing each
other, but separated by an insulator.

When DC voltage is applied to the capacitor, an electric charge is
stored on each electrode.

While the capacitor is charging up, current flows.

The current will stop flowing when the capacitor has fully charged.

10. LED:
A light-emitting diode (LED) is an electronic light source.

LEDs are used as indicator lamps in many kinds of electronics and
increasingly for lighting.

LEDs are based on the semiconductor diode.

The longer lead is the Anode side and the short one is the Cathode
side.

11. TRANSISTOR:
A transistor is a semiconductor device used to amplify and switch
electronic signals and electrical power.

It is composed of semiconductor material with at least three
terminals for connection to an external circuit.

12. BUZZER :The buzzer is used for audible indication for valid user and error
situation and alarm mode.
As soon as pin of the micro controller goes high, the buzzer or
beeper is an audio signaling device, which may be mechanical.
Typical uses of buzzers and beepers include alarm devices, timers.

13. RELAY INTERFACE :A relay is an electrical switch that opens and closes under the
control of another electrical circuit.
The switch is operated by an electromagnet to open or close one or
many sets of contacts.
A relay will switch one or more poles, each of whose contacts can
be thrown by energizing the coil in three ways:a) Normally open
b) Normally closed
c) Change over

14. ADC:
ADC0804 is an 8 bit successive approximation analogue to digital
converter.

The pin out diagram of ADC0804 is shown in the figure below:

15. TEMPERATURE SENSOR(LM35):
The LM35 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the Celsius
(Centigrade) temperature.

The LM35 does not require any external calibration or trimming to
provide typical accuracies of 1⁄4˚Cat room temperature.

16. LCD DISPLAY INTERFACE



LCD (Liquid Crystal Display) screen is an electronic
display module and find a wide range of applications.
A 16x2 LCD display is very basic module and is very
commonly used in various devices and circuits.
A 16x2 LCD means it can display 16 characters per line and
there are 2 such lines.
Two registers in use:- command register and data register.

17. DIODE:
A diode is a semiconductor device which allows current to flow
through it in only one direction.

Although a transistor is also a semiconductor device, it does not
operate the way a diode does.

A diode is specifically made to allow current to flow through it in
only one direction.

18. OPTO COUPLER:
An opt coupler is an electronic component that transfers an
electrical signal or voltage from one part of a circuit to another, or
from one circuit to another, while electrically isolating the two
circuits from each other.

It consists of an infrared emitting LED chip that is optically in-line
with a light-sensitive silicon semiconductor chip, all enclosed in the
same package.

19. EEPROM:


EEPROM stands for Electrically Erasable Programmable ReadOnly Memory.
It has non-volatile memory used in computers and other electronic
devices to store small amounts of data that must be saved.
When larger amounts of static data are to be stored (such as in USB
flash drives) a specific type of EEPROM such as flash memory is
more economical than traditional EEPROM devices.

20. BLOCK DIAGRAM

21. FLOW CHART

22. CIRCUIT DIAGRAM

23. CIRCUIT DESCRIPTION:
ADC0804 is connected as shown in the circuit diagram. Here the
input is taken from a preset, which gives different analog signals to
the ADC.

The output pins of the ADC are connected to LEDs.

The control pins of the ADC are connected to the microcontroller
AT89C52.

The time taken by the ADC to convert analog data into digital form
is dependent on the frequency of clock source.

ADC0804 can be given clock from external source.

24. 
It also has an internal clock. To use the internal clock a capacitor
and resistor is connected to pin 19 and 4 as shown in the circuit
diagram.

The frequency is given by the relation f= 1/ (1.1RC).

The circuit uses a resistance of 10k and a capacitor of 150pF to
generate clock for ADC0804.

Vin, which is the input pin, is connected to a preset to provide
analog input.

25. ADVANTAGES:
This project can be used in Home.

This project can be used in Industry.

This will help in saving the energy / electricity.

To monitor the environments that is not comfortable, or possible,
for humans to monitor, especially for extended periods of time.

Prevents waste of energy when it’s not hot enough for a fan to be
needed.

To assist people who are disabled to adjust the fan speed
automatically.

26. DISADVANTAGES:
It can only be maintained by technical person. Thus, it becomes
difficult to be maintained.

Due to temperature variation, after sometimes its efficiency may
decrease.

27. FUTURE SCOPE:
We can monitor more parameters like humidity, light and at the
same time control them.

We can send this data to a remote location using mobile or internet.

We can draw graphs of variations in these parameters using
computer.

When temperature exceeds the limit, a call will be dialed to the
respective given number by an automatic Dialer system.